Operating vehicles as a group, such as platoons (sometimes also called convoys) is not new, but has become an area of research for applications such as autonomous vehicles and automated highways. Platoons and convoys are familiar in military applications for a variety of vehicle types and terrain, but for roadway travel, research is more recent.
The general concept of a platoon of vehicles on a roadway is that the vehicles travel at a synchronized speed. The goal is to reduce traffic accidents, increase road capacity, and provide more efficient travel. The efficiency benefit results in part from reduced aerodynamic drag. When a vehicle operates in the wake of another vehicle, both vehicles experience a reduction in aerodynamic drag. This effect applies, at least to some extent, to all vehicle types from cars to large trucks.
The composition of a platoon need not be fixed. The platoon may include a wide variety of vehicle types and sizes. Vehicles can join and leave a platoon.
As compared to random traffic, platoons control the distances between vehicles by using automated control processes. This allows for a closer headway between vehicles by eliminating reaction distance needed for human response. This capability allows many cars or trucks to accelerate or brake simultaneously.
To optimize aerodynamic drag and thus fuel efficiency, a platoon should drive with very little gap between vehicles, such as one meter or less. However, other factors limit how close the spacing in a platoon can be. For example, the response time of vehicle controls and variations in braking capability must be taken into account, so that vehicles do not hit each other during acceleration, braking, or turning events. Safety considerations regarding human operated vehicles that that might attempt to insert themselves into a platoon may also limit how closely vehicles within a platoon can operate.